收藏本站
Application Note 9871
40
1. Without power sharing, the on-chip power dissipation
would be 952mW (Equation 6).
35
30
25
V BH
V BL
2. With power sharing, the on-chip power dissipation is
412mW (Equation 7). A power redistribution of 540mW.
On-chip power dissipation without power sharing resistor.
20
15
VBH = -48V
VBL = -24V
RILim = 33.2k ?
P D = ( V BH ) ( 30mA ) + 38.4mW + 13.5mW – ( RL ) ( 30mA )
P D = 952mW
2
(EQ. 6)
10
On-chip power dissipation with 600 ? power sharing resistor.
5
V BL
V BH
P D = ( V BH ) ( 30mA ) + 38.4mW + 13.5mW
– ( R L ) ( 30mA ) – ( R PS ) ( 30mA )
0
LOOP RESISTANCE ( ? )
P D = 412mW
2
2
(EQ. 7)
FIGURE 3. BATTERY SELECTION (DUAL SUPPLY SYSTEMS)
The design trade-off in using the power sharing resistor is
loop length verses on-chip power dissipation.
Setup
1. Reference Test #1 “Power Supply Current Veri?cation”
TIP
UniSLIC14
V TX
and the results in Table 1.
Veri?cation
RING
V RX
1. Notice for the onhook condition (extremely long line) that
all the current is provided by V BH. This feature enables
onhook transmission on the longest loop for a given
battery voltage.
2. Notice for a 600 ? load, the current is shared by both V BH
ON SHORT LOOPS, THE
MAJORITY OF CURRENT
FLOWS OUT THE V BL PIN
V BL
R PS
-48V
V BH
-48V
and V BL . If tip and ring are shorted, then most of the loop
current will come from V BL .
3. Notice the same is true for the reverse active state.
Discussion (Power Sharing)
Power sharing is a method of redistributing the power away
from the SLIC in short loop applications. The total system
power is the same, but the die temperature of the SLIC is
much lower. Power sharing becomes important if the
application has a single battery supply (-48V on hook
requirements for faxes and modems) and the possibility of
high loop currents (reference Figure 4). This technique
would prevent the SLIC from getting too hot and thermally
shutting down on short loops.
The power dissipation in the SLIC is the sum of the smaller
quiescent supply power and the much larger power that
results from the loop current. The power that results from the
loop current is the loop current times the voltage across the
SLIC. The power sharing resistor (R PS ) reduces the voltage
across the SLIC, and thereby the on-chip power dissipation.
The voltage across the SLIC is reduced by the voltage drop
across R PS . This occurs because R PS is in series with the
loop current and the negative supply.
A mathematical veri?cation follows:
Given: V BH = V BL = -48V, Loop current = 30mA, R L (load
across tip and ring) = 600 ? , Quiescent battery power =
(48V) (0.8mA) = 38.4mW, Quiescent VCC power = (5V)
(2.7mA) = 13.5mW, Power sharing resistor = 600 ? .
5
FIGURE 4. POWER SHARING (SINGLE SUPPLY SYSTEMS)
Test #6, Ring Trip Veri?cation
This test will verify the ringing function of the HC5514X. A
telephone, a battery referenced AC signal source, and a
BNC to banana adaptor are the only additional hardware
required to complete the test.
Discussion
The 600 ? termination is not necessary for this test since the
phone provides this nominal impedance when offhook. If the
RSYNC_REV pin is grounded, the ring relay driver pin
(RRLY) pin goes low after the SLIC is placed in the ringing
state. This will energize the ring relay. The ring relay
disconnects tip and ring from the phone and connects the
path for the ringing signal. The D T and D R comparator inputs
will sense the ?ow of DC loop current, enabling the ring trip
comparator to sense when the phone is either onhook or
offhook. When an offhook condition is detected, the
HC5514X will automatically disconnect the ringing signal to
the phone at zero current crossing. This reduces impulse
noise to the system. Refer to the HC5514 Subscriber Line
Interface Circuit electrical data sheet for more information
about the functionality of the ring trip detector.
Setup
1. Connect the power supplies to the Evaluation board.
2. Set V BH to -48V, V BL to -24V and V CC to +5V.
发布紧急采购，3分钟左右您将得到回复。

采购需求

(若只采购一条型号，填写一行即可)

发布成功！您可以继续发布采购。也可以进入我的后台，查看报价

发布成功！您可以继续发布采购。也可以进入我的后台，查看报价

*型号 *数量 厂商 批号 封装
添加更多采购

我的联系方式

*
*
*
相关PDF资料
HC55185EVAL2 EVALUATION PLATFORM HC55185+T
HE1015 BOOT CIRCUIT BREAKER 1POLE CLEAR
HE1020 BOOT CIRCUIT BREAKER 2POLE CLEAR
HE1050 BOOT CIRCUIT BREAKER 3POLE CLEAR
HE1070 BOOT CIRCUIT BREAKER 3POLE CLEAR
HFW30R-1STE1 HFW30R-1STE1-FFC/FPC CONN
HFW30S-2STE1 HFW30S-2STE1-USING HFW-P5SL
HHG FUSEHOLDER AUTO INLINE FOR ATC
相关代理商/技术参数
HC5515 制造商:INTERSIL 制造商全称:Intersil Corporation 功能描述:ITU CO/PABX SLIC with Low Power Standby
HC5515_06 制造商:INTERSIL 制造商全称:Intersil Corporation 功能描述:ITU CO/PABX SLIC with Low Power Standby
HC55150 制造商:INTERSIL 制造商全称:Intersil Corporation 功能描述:Low Power Universal SLIC Family
HC55150CB 制造商:Rochester Electronics LLC 功能描述:LOW PWR SLIC,POL REV/METERING,55DB BALANCE - Bulk
HC55150CBZ 功能描述:电信线路管理 IC LW PWR SLIC POLV/MTRING 55DB RoHS:否 制造商:STMicroelectronics 产品:PHY 接口类型:UART 电源电压-最大:18 V 电源电压-最小:8 V 电源电流:30 mA 最大工作温度:+ 85 C 最小工作温度:- 40 C 安装风格:SMD/SMT 封装 / 箱体:VFQFPN-48 封装:Tray
HC55150CM 制造商:Rochester Electronics LLC 功能描述:LOW PWR SLIC,POL REV/METERING,55DB BALANCE - Bulk
HC55150CMZ 功能描述:电信线路管理 IC LW PWR SLIC POLV/MTRING 55DB RoHS:否 制造商:STMicroelectronics 产品:PHY 接口类型:UART 电源电压-最大:18 V 电源电压-最小:8 V 电源电流:30 mA 最大工作温度:+ 85 C 最小工作温度:- 40 C 安装风格:SMD/SMT 封装 / 箱体:VFQFPN-48 封装:Tray
HC55151 制造商:INTERSIL 制造商全称:Intersil Corporation 功能描述:Low Power Universal SLIC Family